U.S. patent number 10,214,471 [Application Number 15/778,562] was granted by the patent office on 2019-02-26 for method for producing propylene glycol from propene and hydrogen peroxide.
This patent grant is currently assigned to Evonik Degussa GmbH. The grantee listed for this patent is EVONIK DEGUSSA GMBH. Invention is credited to David Bolz, Sebastian Imm, Bernd Jaeger, Hans-Jurgen Kohle, Georg Friedrich Thiele, Holger Wiederhold.
United States Patent |
10,214,471 |
Wiederhold , et al. |
February 26, 2019 |
Method for producing propylene glycol from propene and hydrogen
peroxide
Abstract
The process for preparing 1,2-propanediol from propene and
hydrogen peroxide comprises the steps of a) reacting propene with
hydrogen peroxide in the presence of a catalyst mixture comprising
a phase transfer catalyst and a heteropolytungstate, wherein the
reaction is carried out in a liquid mixture comprising an aqueous
phase having a pH of at most 6 and an organic phase, b) separating
the biphasic mixture from step a) into an aqueous phase and an
organic phase comprising propene oxide, c) recycling the propene
oxide present in the separated organic phase into the reaction of
step a) and d) separating 1,2-propanediol from the aqueous phase
separated in step b).
Inventors: |
Wiederhold; Holger (Darmstadt,
DE), Bolz; David (Frankfurt, DE), Jaeger;
Bernd (Bickenbach, DE), Kohle; Hans-Jurgen
(Mainhausen, DE), Imm; Sebastian (Bad Vilbel,
DE), Thiele; Georg Friedrich (Friedberg,
DE) |
Applicant: |
Name |
City |
State |
Country |
Type |
EVONIK DEGUSSA GMBH |
Essen |
N/A |
DE |
|
|
Assignee: |
Evonik Degussa GmbH (Essen,
DE)
|
Family
ID: |
54754460 |
Appl.
No.: |
15/778,562 |
Filed: |
November 1, 2016 |
PCT
Filed: |
November 01, 2016 |
PCT No.: |
PCT/EP2016/076270 |
371(c)(1),(2),(4) Date: |
May 23, 2018 |
PCT
Pub. No.: |
WO2017/089075 |
PCT
Pub. Date: |
June 01, 2017 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20180354878 A1 |
Dec 13, 2018 |
|
Foreign Application Priority Data
|
|
|
|
|
Nov 25, 2015 [EP] |
|
|
15196268 |
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C07C
29/48 (20130101); C07C 29/106 (20130101); C07C
29/76 (20130101); C07C 29/48 (20130101); C07C
31/205 (20130101); C07C 29/76 (20130101); C07C
31/205 (20130101); C07C 29/106 (20130101); C07C
31/205 (20130101) |
Current International
Class: |
C07C
29/48 (20060101); C07C 29/76 (20060101); C07C
29/80 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
195 07 584 |
|
Sep 1996 |
|
DE |
|
0 100 119 |
|
Feb 1984 |
|
EP |
|
0 230 949 |
|
Aug 1987 |
|
EP |
|
0 659 473 |
|
Jun 1995 |
|
EP |
|
0 757 045 |
|
Feb 1997 |
|
EP |
|
1 247 806 |
|
Oct 2002 |
|
EP |
|
1 489 074 |
|
Dec 2004 |
|
EP |
|
WO 02/085873 |
|
Oct 2002 |
|
WO |
|
WO 03/016296 |
|
Feb 2003 |
|
WO |
|
WO 03/018567 |
|
Mar 2003 |
|
WO |
|
WO 03/093255 |
|
Nov 2003 |
|
WO |
|
WO 2004/018088 |
|
Mar 2004 |
|
WO |
|
WO 2004/048335 |
|
Jun 2004 |
|
WO |
|
WO 2004/048354 |
|
Jun 2004 |
|
WO |
|
WO 2004/048355 |
|
Jun 2004 |
|
WO |
|
WO 2005/000827 |
|
Jan 2005 |
|
WO |
|
WO 2005/103024 |
|
Nov 2005 |
|
WO |
|
WO 2008/141734 |
|
Nov 2008 |
|
WO |
|
WO 2011/063937 |
|
Jun 2011 |
|
WO |
|
Other References
International Search Report for PCT/EP2016/076270 filed Nov. 1,
2016. cited by applicant .
Written Opinion of the International Searching Authority for
PCT/EP2016/076270 filed Nov. 1, 2016. cited by applicant .
International Preliminary Report on Patentability for
PCT/EP2016/076270 filed Nov. 1, 2016. cited by applicant .
Chowdhury, et al, "Recovery of Homogeneous Polyoxometallate
Catalysts from Aqueous and Organic Media by a Mesoporous Ceramic
Membrane without Loss of Catalytic Activity," Chem. Eur. J.
12(11):3061-3066 (Apr. 2006). cited by applicant .
Guojie, et al., "Factors Affecting Propylene Epoxidation Catalyzed
by Reaction-Controlled Phase-Transfer Catalyst," Chinese Journal of
Catalysis 26:1005-1010 (Nov. 2005). cited by applicant .
Kaur, et al., "Poloxometalate-catalysed epoxidation of propylene
with hydrogen peroxide: microemulsion versus biphasic process,"
Catalysis Communications 5(11): 709-713 (Nov. 2004). cited by
applicant .
Li, et al., "Influence of composition of
heteropolyphophatotungstate catalyst on epoxidation of propylene,"
Journal of Molecular Catalysis A: Chemical 218(2):247-252 (Aug.
(2004). cited by applicant .
Luthra, et al., "Homogeneous phase transfer catalyst recovery and
re-use using solvent resistant membranes," Journal of Membrane
Science 201:65-75 (2002). cited by applicant .
Venturello, et al., "A New, Effective Catalytic System for
Epoxidation of Olefins by Hydrogen Peroxide under Phase-Transfer
Conditions," J. Org. Chem. 483831-3833 (1983). cited by applicant
.
U.S. Appl. No. 15/329,626, filed Jan. 26, 2017, US-2017/0210718 A1,
Jul. 27, 2017, Stochinol. cited by applicant .
U.S. Appl. No. 15/570,167, filed Oct. 15, 2017, US-2018/0134676 A1,
May 27, 2018, Jahn. cited by applicant .
U.S. Appl. No. 15/778,318, filed May 23, 2018, Brendel. cited by
applicant .
U.S. Appl. No. 15/778,337, filed May 23, 2018, Pascaly. cited by
applicant .
U.S. Appl. No. 15/778,425, filed May 23, 2018, Hofen. cited by
applicant .
U.S. Appl. No. 16/070,873, filed Jul. 18, 2018, Schmidt. cited by
applicant .
Notice of Allowance dated Oct. 16, 2018 for copending U.S. Appl.
No. 15/778,318. cited by applicant.
|
Primary Examiner: Witherspoon; Sikarl A
Attorney, Agent or Firm: Michael A. Sanzo, LLC
Claims
The invention claimed is:
1. A process for preparing 1,2-propanediol from propene and
hydrogen peroxide, comprising the steps of: a) reacting propene
with hydrogen peroxide in the presence of a catalyst mixture
comprising a phase transfer catalyst and a heteropolytungstate,
wherein the reaction is carried out in a biphasic liquid mixture
comprising an aqueous phase having a pH of at most 6 and an organic
phase; b) separating the biphasic mixture from step a) into an
aqueous phase P1 and an organic phase P2 comprising propene oxide;
c) recycling the propene oxide present in the separated organic
phase P2 into the reaction of step a); and d) separating
1,2-propanediol from the aqueous phase P1 separated in step b).
2. The process of claim 1, wherein the heteropolytungstate present
in the organic phase P2 separated in step c) is recycled into the
reaction of step a).
3. The process of claim 1, wherein the pH of the aqueous phase in
step a) is maintained in the range of 1.0 to 3.5.
4. The process of claim 1, wherein the aqueous phase P1 is
separated by nanofiltration in step d) into a retentate enriched in
heteropolytungstate and a permeate depleted in heteropolytungstate,
the retentate is recycled into the reaction of step a) and
1,2-propanediol is separated from the permeate.
5. The process of claim 1, wherein the reaction in step a) is
carried out in the presence of at least one solvent having a
boiling point of more than 100.degree. C. and a water solubility at
20.degree. C. of less than 250 mg/kg.
6. The process of claim 5, wherein the solvent comprises an
epoxidized fatty acid methyl ester.
7. The process of claim 5, wherein the solvent comprises an
alkylated aromatic hydrocarbon having 8 to 12 carbon atoms.
8. The process of claim 1, wherein the organic phase P2 separated
in step b) is completely or partly recycled into the reaction of
step a).
9. The process of claim 1, wherein the organic phase P2 is
separated completely or partly by nanofiltration in step c) into a
retentate enriched in heteropolytungstate and a permeate depleted
in heteropolytungstate and the retentate enriched in
heteropolytungstate is recycled into the reaction of step a).
10. The process of claim 9, wherein the organic phase P2 is
separated by nanofiltration into the retentate enriched in
heteropolytungstate and the permeate depleted in
heteropolytungstate, a stream S1 comprising unreacted propene and
propene oxide formed as an intermediate is separated by
distillation from the permeate depleted in heteropolytungstate and
this stream S1 is recycled into the reaction of step a).
11. The process of claim 9, wherein the organic phase P2 is
separated by distillation into a stream S1 comprising unreacted
propene and propene oxide formed as intermediate, and a stream S2
depleted in propene and propene oxide, the stream S2 is separated
by nanofiltration into the retentate enriched in
heteropolytungstate and the permeate depleted in
heteropolytungstate and the stream S1 is recycled into the reaction
of step a).
12. The process of claim 1, wherein in step d), prior to the
separation of 1,2-propanediol, peroxides are removed by catalytic
hydrogenation.
13. The process of claim 1, wherein the aqueous phase P1 separated
in step b) is brought into contact with liquid propene in step d)
to obtain an aqueous phase P3 and an organic phase P4, the organic
phase P4 is recycled into the reaction of step a) and
1,2-propanediol is separated from the aqueous phase P3.
14. The process of claim 13, wherein propene is supplied to the
process only in step d).
15. The process of claim 1, wherein propene is used in a mixture
with propane.
16. The process of claim 1, wherein step a) is carried out
continuously and the concentration of hydrogen peroxide in the
aqueous phase is in the range of 0.1 to 5% by weight.
17. The process of claim 1, wherein step a) is carried out
continuously in a loop reactor having fixed internals, and the
biphasic liquid mixture is conducted through the loop reactor at a
flow rate which generates a turbulent flow over the internals.
18. The process of claim 1, wherein the heteropolytungstate is a
polytungstophosphate.
19. The process of claim 18, wherein the polytungstophosphate in
step a) is generated in situ from phosphoric acid and sodium
tungstate.
20. The process of claim 19, wherein phosphoric acid and sodium
tungstate are used in a molar ratio of from 1:2 to 10:1.
21. The process of claim 1, wherein the phase transfer catalyst
comprises at least one salt having a tertiary or quaternary
ammonium ion of the structure R.sup.1R.sup.2R.sup.3R.sup.4N.sup.+,
wherein: R.sup.1 is a Y--O(C.dbd.O)R.sup.5 group, wherein Y is a
group CH.sub.2CH.sub.2, CH(CH.sub.3)CH.sub.2 or
CH.sub.2CH(CH.sub.3) and R.sup.5 is an alkyl group or alkenyl group
having 11 to 21 carbon atoms; R.sup.2 is hydrogen or an alkyl group
having 1 to 4 carbon atoms; and R.sup.3 and R.sup.4 are each
independently R.sup.1, an alkyl group having 1 to 4 carbon atoms or
Y--OH.
22. The process of claim 1, wherein step b) is carried out in the
presence of a gas phase and the oxygen content of this gas phase is
maintained at less than 7% by volume by supplying inert gas and
withdrawal of a gas stream.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
The present application is US national stage of international
application PCT/EP2016/076270, which had an international filing
date of Nov. 1, 2016, and which was published on Jun. 1, 2017.
Priority is claimed to European application EP 15196268.5, filed on
Nov. 25, 2015.
The invention relates to a process for preparing 1,2-propanediol
from propene and hydrogen peroxide which does not require isolation
and purification of propene oxide.
1,2-Propanediol is prepared industrially by reacting propene oxide
with water. Propene oxide is prepared industrially by epoxidation
of propene. In the established process, propene oxide is isolated
from the reaction mixture of the epoxidation and purified before it
is converted to 1,2-propanediol.
In the course of preparation of propene oxide by the HPPO process,
in which propene and hydrogen peroxide are reacted in the presence
of a titanium silicalite in methanol as solvent, 1,2-propanediol
and 1,2-propanediol monomethyl ether are obtained as
by-products.
WO 04/009568 proposes producing a crude propene oxide having a
content of 95 to 99%, by distillation from the reaction mixture of
the HPPO process, this being reacted with water without further
purification to give 1,2-propanediol and to purify 1,2-propanediol
together with by-product separated from the bottom product of the
distillation. Also in this process, propene oxide is isolated and
converted to 1,2-propanediol in a separate reactor.
J. Guojie et al. in Chinese Journal of Catalysis 26 (2005)
1005-1010 describe the epoxidation of propene with hydrogen
peroxide in the presence of a quaternary ammonium
heteropolyphosphatotungstate as catalyst in a biphasic reaction
mixture with CHCI3 or a mixture of toluene and tributyl phosphate
as solvent. To improve the selectivity for propene oxide,
K.sub.2HPO.sub.4 or Na.sub.2HPO.sub.4 are added as additive.
Without addition of an additive, more 1,2-propanediol than propene
oxide is obtained with selectivities for 1,2-propanediol of 41.2
and 56.3%.
J. Kaur et al. in Catal. Commun. 5 (2004) 709-713 describe the
epoxidation of propene with hydrogen peroxide in the presence of
methyltrioctylammonium peroxopolytungstate. The epoxidation is
carried out either in a microemulsion produced by adding the
surfactant Brij.RTM. 30 or in a biphasic system with
1,2-dichloroethane as solvent. For the biphasic system, for reuse
of the catalyst, the phases are separated, the organic phase is
extracted with water and propene oxide and unreacted propene are
removed by purging with nitrogen at 60.degree. C. For the
microemulsion, a membrane ultrafiltration is proposed for
separating catalyst and water in order to reuse the catalyst.
S. R. Chowdhury et al., Chem. Eur. J. 12 (2006) 3061-3066 describe
an epoxidation of cyclooctene with hydrogen peroxide in the
presence of
[CH.sub.3N(C.sub.8H.sub.17).sub.3].sub.12[WZn.sub.3(ZnW.sub.9O.sub.34).su-
b.2] as catalyst and toluene as solvent with removal of the
catalyst by filtration over alumina membranes having average pore
radii of 2.3 nm and 4.3 nm. Using the alumina membrane having an
average pore radius of 2.3 nm,
Na.sub.12[WZn.sub.3(ZnW.sub.9O.sub.34).sub.2] was also removed from
an aqueous solution.
S. S. Luthra et al., J. Membr. Sci. 201 (2002) 65-75 describe the
separation of the phase transfer catalysts tetra-n-butylammonium
bromide and tetra-n-octylammonium bromide from toluene by
nanofiltration.
It has now been found that propene can be reacted with hydrogen
peroxide in high yields and selectivities in one stage to give
1,2-propanediol if the reaction is carried out using a combination
of a phase transfer catalyst and a heteropolytungstate in a
reaction mixture having two liquid phases, in which the pH of the
aqueous phase is maintained below 6, the propene oxide present in
the organic phase of the reaction mixture is recycled into the
reactor and 1,2-propanediol is separated from the aqueous
phase.
Accordingly, the invention relates to a process for preparing
1,2-propanediol from propene and hydrogen peroxide comprising the
steps of a) reacting propene with hydrogen peroxide in the presence
of a catalyst mixture comprising a phase transfer catalyst and a
heteropolytungstate, wherein the reaction is carried out in a
liquid mixture comprising an aqueous phase having a pH of at most 6
and an organic phase, b) separating the biphasic mixture from step
a) into an aqueous phase P1 and an organic phase P2, c) recycling
the propene oxide present in the separated organic phase P2 into
the reaction of step a) and d) separating 1,2-propanediol from the
aqueous phase P1 separated in step b).
In the process according to the invention, propene is reacted with
hydrogen peroxide in step a) in the presence of a catalyst mixture
comprising a phase transfer catalyst and a heteropolytungstate. The
reaction is carried out in a liquid mixture comprising two liquid
phases, an aqueous phase and an organic phase.
Propene can be used in pure form or in a mixture with propane,
wherein the proportion of propane may be up to 20 mol %. The
proportion of propane in the propene used is preferably less than 5
mol %.
Hydrogen peroxide is preferably used in the form of an aqueous
solution, preferably with a hydrogen peroxide content of 10 to 80%
by weight, particularly preferably 30 to 70% by weight. In the
process according to the invention, the hydrogen peroxide crude
product is obtained in the extraction stage of the anthraquinone
process for producing hydrogen peroxide may be used.
The aqueous phase comprises water, unreacted hydrogen peroxide and
1,2-propanediol formed. The organic phase comprises propene, and
propene oxide formed as intermediate and can in addition comprise
propane originating from the propene used. In addition, the organic
phase may comprise at least one solvent immiscible with water.
The catalyst mixture used in the process according to the invention
comprises a heteropolytungstate, wherein the heteroatom is
preferably phosphorus or arsenic and is particularly preferably
phosphorus, i.e. the heteropolytungstate is particularly preferably
a polytungstophosphate. Heteropolytungstates are known from the
prior art to those skilled in the art. Special preference is given
to polytungstophosphates having a molar ratio of phosphorus to
tungsten in the range of from 1:2 to 1:12. Polytungstophosphate is
preferably generated in situ in the liquid mixture in step a) from
phosphoric acid and sodium tungstate, wherein phosphoric acid and
sodium tungstate are preferably used at a molar ratio of phosphorus
to tungsten in the range of from 1:2 to 10:1 and particularly of
from 4:1 to 8:1. Peroxotungstates and peroxotungstophosphates, for
example PO.sub.4[WO(O.sub.2).sub.2].sub.4.sup.3- and
HPO.sub.4[WO(O.sub.2).sub.2].sub.2.sup.2- and also partially
protonated forms thereof, are formed from a polytungstophosphate
with hydrogen peroxide in the aqueous phase.
The catalyst mixture used in the process according to the invention
also comprises a phase transfer catalyst. The phase transfer
catalyst comprises a cation or a compound which forms a cation in
the aqueous phase, wherein the cation can form an organic phase
soluble salt with a peroxotungstate or heteropolyperoxotungstate.
The phase transfer catalyst preferably comprises a singly-charged
cation or a compound which forms a singly-charged cation in the
aqueous phase. Suitable as phase transfer catalyst are quaternary
ammonium salts, tertiary amines or quaternary phosphonium salts.
Suitable quaternary ammonium salts are tetraalkylammonium salts
having in total at least 12 carbon atoms in the alkyl groups, for
example dodecyltrimethylammonium salts, hexadecyltrimethylammonium
salts, octadecyltrimethylammonium salts, methyltributylammonium
salts and methyltrioctylammonium salts. Quaternary ammonium salts
with mono- or divalent anions are suitable, for example chloride,
bromide, nitrate, sulphate, hydrogenphosphate, dihydrogenphosphate,
methylsulphonate, methylsulphate and ethylsulphate. Suitable
tertiary amines are dodecyldimethylamine, hexadecyldimethylamine,
octadecyldimethylamine, tributylamine and trioctylamine. The phase
transfer catalyst is preferably used in an amount which results in
a molar ratio in the liquid mixture of phase transfer catalyst to
tungsten in the range of from 0.2:1 to 3:1 and particularly
preferably of from 0.4:1 to 1:1, wherein the molar ratio refers to
the cations or compounds forming cations contained in the phase
transfer catalyst used and to the amount of tungsten used.
In a preferred embodiment, the phase transfer catalyst comprises at
least one salt having a tertiary or quaternary ammonium ion of the
structure R.sup.1R.sup.2R.sup.3R.sup.4N.sup.+, where R.sup.1 is a
Y--O(C.dbd.O)R.sup.5 group, where Y is one of the groups
CH.sub.2CH.sub.2, CH(CH.sub.3)CH.sub.2 and CH.sub.2CH(CH.sub.3) and
R.sup.5 is an alkyl group or alkenyl group having 11 to 21 carbon
atoms,
R.sup.2 is hydrogen or an alkyl group having 1 to 4 carbon atoms,
and
R.sup.3 and R.sup.4 are each independently R.sup.1, an alkyl group
having 1 to 4 carbon atoms or Y--OH.
Preference is given to quaternary ammonium salts having
methylsulphate as anion, in which R.sup.2 is a methyl group and
R.sup.5 is a linear alkyl group or alkenyl group. Particular
preference is given to the salts
(CH.sub.3).sub.3N.sup.+CH.sub.2CH.sub.2O(C.dbd.O)R.sup.5CH.sub.3OSO.sub.3-
.sup.-,
(CH.sub.3).sub.2N.sup.+(CH.sub.2CH.sub.2OH)(CH.sub.2CH.sub.2O(C.db-
d.O)R.sup.5) CH.sub.3OSO.sub.3.sup.-,
(CH.sub.3).sub.2N.sup.+(CH.sub.2CH.sub.2O(C.dbd.O)R.sup.5).sub.2
CH.sub.3OSO.sub.3.sup.-,
CH.sub.3N.sup.+(CH.sub.2CH.sub.2OH).sub.2(CH.sub.2CH.sub.2O(C.dbd.O)R.sup-
.5) CH.sub.3OSO.sub.3.sup.-,
CH.sub.3N.sup.+(CH.sub.2CH.sub.2OH)(CH.sub.2CH.sub.2O(C.dbd.O)R.sup.5).su-
b.2 CH.sub.3OSO.sub.3.sup.-,
CH.sub.3N.sup.+(CH.sub.2CH.sub.2O(C.dbd.O)R.sup.5).sub.3
CH.sub.3OSO.sub.3.sup.-,
(CH.sub.3).sub.3N.sup.+CH.sub.2CH(CH.sub.3)O(C.dbd.O)R.sup.5
CH.sub.3OSO.sub.3.sup.-,
(CH.sub.3).sub.2N.sup.+(CH.sub.2CH(CH.sub.3)OH)(CH.sub.2CH(CH.sub.3)O(C.d-
bd.O)R.sup.5) CH.sub.3OSO.sub.3.sup.- and
(CH.sub.3).sub.2N.sup.+(CH.sub.2CH(CH.sub.3)O(C.dbd.O)R.sup.5).sub.2CH.su-
b.3OSO.sub.3.sup.-, in which R.sup.5 is in each case a linear alkyl
group or alkenyl group having 11 to 21 carbon atoms. Special
preference is given to the salt
(CH.sub.3).sub.2N.sup.+(CH.sub.2CH(CH.sub.3)O(C.dbd.O)R.sup.5).sub.2
CH.sub.3OSO.sub.3.sup.- in which R.sup.5 is an alkyl group or
alkenyl group having 11 to 17 carbon atoms. The phase transfer
catalysts of this embodiment may be prepared by esterifying
ethanolamine, isopropanolamine, diethanolamine, diisopropanolamine,
triethanolamine or triisopropanolamine with a fatty acid and
subsequent quaternization with dimethyl sulphate and have the
advantage, compared to tetraalkylammonium salts, that they are
readily biodegradable and the waste water resulting from the
process according to the invention can be introduced into a
biological treatment plant without further pretreatment. Using the
preferred salts with methylsulphate as anion, the corrosivity of
the reaction mixture can also be reduced in comparison to
tetraalkylammonium halides. In this embodiment, preferably the
phase transfer catalyst mixed with at least one solvent selected
from ethanol and 2-propanol is added to the liquid mixture of the
reaction. By using this solvent, the phase transfer catalyst can be
more easily dosed and distributed in the liquid mixture.
The phase transfer catalyst and the heteropolytungstate can be fed
to the reaction as a mixture or separately from each other. Phase
transfer catalyst and heteropolytungstate are preferably fed
separately in step a).
The reaction of propene with hydrogen peroxide is carried out at a
pH of the aqueous phase of at most 6. The pH of the aqueous phase
is preferably maintained in the range from 1.0 to 3.5, particularly
preferably in the range from 2.0 to 3.0. The pH can be maintained
in this range by addition of acid, preferably sulphuric acid or
phosphoric acid, or by addition of base, preferably aqueous sodium
hydroxide solution. The term pH here refers to the apparent pH
measured with a glass electrode, wherein the glass electrode has
been calibrated with aqueous buffer solutions. By adjusting to a pH
in the preferred range, high selectivity for 1,2-propanediol can be
achieved and enrichment of propene oxide in the aqueous phase can
be prevented, which simplifies the subsequent separation of
1,2-propanediol from the aqueous phase.
The reaction of propene with hydrogen peroxide is preferably
carried out with a molar excess of propene, wherein propene is
preferably used in a molar ratio of propene to hydrogen peroxide of
from 1.1:1 to 10:1.
The reaction is carried out preferably at a temperature in the
range of 30 to 100.degree. C., particularly preferably 70 to
90.degree. C. The reaction is carried out preferably at a pressure
which is higher than the saturated vapour pressure of propene at
the temperature of the reaction such that the major portion of the
propene is present in the organic phase of the liquid mixture.
The reaction of propene with hydrogen peroxide can be carried out
with or without addition of solvents. The reaction is preferably
carried out in the presence of at least one solvent having a
boiling point of more than 100.degree. C., preferably more than
120.degree. C., and a water solubility at 20.degree. C. of less
than 250 mg/kg. The solvents used may be alcohols having one or
more hydroxyl groups, ethers, esters, ketones or alkylated aromatic
hydrocarbons. By using a solvent, the proportion of
heteropolytungstate in the organic phase can be increased. The
proportion of solvent is preferably selected such that the
proportion of solvent in the organic phase during the reaction is
in the range of 10 to 90% by weight.
In a particularly preferred embodiment, the solvent comprises an
epoxidized fatty acid methyl ester. For this purpose, in place of
the epoxidized fatty acid methyl ester, the corresponding fatty
acid methyl ester with unsaturated fatty acid groups can also be
used, which is converted to the epoxidized fatty acid methyl ester
in the liquid mixture of step a). Most preferred are epoxidized
fatty acid methyl esters whose fatty acid groups originate from
vegetable oils, particularly soybean oil. The epoxidized fatty acid
methyl esters have the advantage that they are poorly soluble in
the aqueous phase and no separation of solvent from the aqueous
phase of the reaction is required.
In a further preferred embodiment, the solvent comprises an
alkylated aromatic hydrocarbon having 8 to 12 carbon atoms.
Suitable alkylated aromatic hydrocarbons are, for example,
1,2-dimethylbenzene (o-xylene), 1,3-dimethylbenzene (m-xylene),
1,4-dimethylbenzene (p-xylene), ethylbenzene,
1,2,3-trimethylbenzene, 1,2,4-trimethylbenzene,
1,3,5-trimethylbenzene (mesitylene), 1-ethyl-2-methylbenzene,
1-ethyl-3-methylbenzene and 1-ethyl-4-methylbenzene and
n-propylbenzene. Preferably hydrocarbon mixtures comprising more
than 50% by weight, particularly preferably more than 80% by
weight, alkylated aromatic hydrocarbons having 8 to 12 carbon atoms
are used as solvent. By using a solvent comprising alkylated
aromatic hydrocarbon having 8 to 12 carbon atoms, an extensive
extraction of the heteropolytungstate into the organic phase of the
reaction mixture can be achieved so that an improved recycling of
the heteropolytungstate with the organic phase and a simplified
recovery of heteropolytungstate from the organic phase of the
reaction of propene with hydrogen peroxide can be achieved.
The phase transfer catalyst, the molar ratio of phase transfer
catalyst to heteropolytungstate, the molar ratio of heteroatom of
the heteropolytungstate to tungsten, the molar ratio of propene to
hydrogen peroxide and type and amount of solvent optionally used
are preferably selected such that as large a portion as possible of
the tungsten present in the liquid mixture is transferred into the
organic phase of the liquid mixture by the phase transfer catalyst.
For this purpose, one of the aforementioned phase transfer
catalysts based on an alkanolamine fatty acid ester is preferably
used in combination with an epoxidized fatty acid methyl ester or a
hydrocarbon mixture with more than 50% by weight alkylated aromatic
hydrocarbons having 8 to 12 carbon atoms as solvent.
The reaction of propene with hydrogen peroxide may be carried out
in batch or continuously, wherein a continuous reaction is
preferred. In a continuous reaction, the concentration of hydrogen
peroxide in the aqueous phase is preferably in the range of 0.1 to
5% by weight, particularly preferably 0.5 to 3% by weight. Such a
concentration of hydrogen peroxide may be adjusted by the selection
of the reaction temperature, the molar ratio of propene to hydrogen
peroxide and the residence time of the liquid mixture in the
reactor in which the reaction takes place.
During the reaction, the liquid mixture is preferably mixed in
order to generate a large phase interface between the aqueous phase
and the organic phase. For this purpose, the reaction is preferably
carried out continuously in a loop reactor having fixed internals,
and the liquid mixture is conducted through the loop reactor at a
flow rate which generates a turbulent flow over the internals.
Baffles, static mixing elements, structured packings or random
packings can be used as internals for this purpose. Alternatively
or in combination to this, the internals used may be heat
exchangers, such as plate heat exchangers or tube bundle heat
exchangers, in which turbulent flow is generated between the plates
or in the tubes of the tube bundles.
In step b) of the process according to the invention, the biphasic
mixture from step a) is separated into an aqueous phase P1 and an
organic phase P2. The separation is preferably carried out in a
settler vessel, and the biphasic mixture can be passed over a
coalescer element comprising a structured packing or random packing
with a surface wetted by the phase present dispersed in the
biphasic mixture, in order to assist the separation.
The liquid phase is separated in step b) preferably in the presence
of a gas phase. The reaction in step a) can lead to a decomposition
of hydrogen peroxide with formation of oxygen and in step b) the
gas phase may then comprise oxygen. In order to avoid the formation
of a flammable gas phase, the oxygen content of this gas phase is
therefore maintained below 7% by volume in step b), preferably by
supplying inert gas and withdrawing a gas stream. The inert gas
used may be nitrogen, argon, carbon dioxide or methane, wherein
nitrogen is preferred.
In step c) of the process according to the invention, the propene
oxide present in the organic phase P2 is recycled into the reaction
of step a), in order to achieve as far as possible complete
conversion of propene to 1,2-propanediol. Preferably, the
heteropolytungstate present in the organic phase P2 is additionally
recycled into the reaction of step a), the portion of the catalyst
mixture present in the organic phase being particularly preferably
substantially completely recycled into step a). Likewise, the
propene present in the organic phase P2 is preferably recycled into
the reaction of step a). If propene is used as a mixture with
propane, the same amount of propane is preferably separated from
the organic phase P2 in the recycling into step a), which is fed to
step a) with the mixture of propene with propane. This way,
enrichment of propane in the organic phase in step a) can be
avoided when the reaction in step a) is performed continuously.
In a preferred embodiment of the process according to the
invention, the organic phase P2 (9) separated in step b) is
completely or partly recycled into the reaction of step a).
In a further preferred embodiment of the process according to the
invention, the organic phase P2 is separated completely or partly
by nanofiltration in step c) into a retentate enriched in
heteropolytungstate and a permeate depleted in heteropolytungstate
and the retentate is recycled into the reaction of step a).
Preferably, the entire organic phase P2 is separated by
nanofiltration into a retentate and a permeate. Corresponding to
the nomenclature recommendation of the IUPAC, the term
nanofiltration here refers to a pressure-driven separation at a
membrane, in which the membrane retains particles and dissolved
molecules having a diameter of less than 2 nm. For the
nanofiltration in step c), a nanofiltration membrane is used which
retains the salt of peroxotungstate or heteroperoxotungstate and
the cation of the phase transfer catalyst in the retentate and
allows propene to pass through with the permeate. The
nanofiltration is then preferably operated such that the
concentration of the salt of peroxotungstate or
heteropolyperoxotungstate and the cation of the phase transfer
catalyst in the retentate does not increase above the saturation
concentration. Membranes based on the polymers polyimide, polyether
sulphone, polyamide and polidimethylsiloxane can be used for the
nanofiltration. Suitable nanofiltration membranes are commercially
available, for example, from Evonik Membrane Extraction Technology
MET under the name PuraMem.RTM. S600, from GMT Membrantechnik under
the name ONF-2, from SolSep under the designations 010306, 030306,
030705 and 030306F, and from AMS Technologies under the name
NanoPro.TM. SX. Preference is given to using one of the composite
membranes known from DE 195 07 584, EP 1 741 481 and WO
2011/067054
The nanofiltration preferably takes place as a cross-flow
filtration, preferably at a temperature in the range of 20 to
90.degree. C., particularly preferably 40 to 80.degree. C. The
transmembrane pressure is preferably 2 to 5 MPa. The pressure on
the retentate side can be up to 10 MPa. The pressure on the
permeate side is preferably selected to be higher than the lowest
pressure in steps a) and b) of the process in order to prevent
outgassing of dissolved components on the permeate side.
In a likewise preferred embodiment, the organic phase P2 is
separated by nanofiltration into a retentate enriched in
heteropolytungstate and a permeate depleted in heteropolytungstate,
a stream S1 comprising unreacted propene and propene oxide formed
as intermediate is separated by distillation from the permeate and
this stream is recycled into the reaction of step a). The
distillation is preferably carried out at a pressure at which
propene can be condensed with the distillate by cooling with water.
Alternatively, the distillation may also be carried out at a lower
pressure, propene oxide and only a portion of the propene can be
condensed with the distillate and the remaining vapour can be
compressed to condense the propene. In this embodiment,
high-boiling by-products and degradation products of the phase
transfer catalyst can be discharged with the bottom product of the
distillation, and enrichment of poorly water-soluble by-products
and impurities in the organic phase are avoided in step a) when the
reaction in step a) is performed continuously. Removing stream S1
by distillation after the nanofiltration prevents further reaction
of propene oxide, formed as intermediate, with the catalyst system
by heating, which leads to by-products. If in step a) of the
process the reaction is carried out in the presence of a solvent,
it is preferred that, subsequent to the distillation for separating
stream S1, the bottom product of this distillation is fed to a
further distillation in which the solvent is separated by
distillation. The solvent separated can be recycled into step a).
If propene is used as a mixture with propane, the distillation is
preferably carried out so that, in addition to stream S1, a further
stream is obtained, consisting essentially of propene and propane,
from which propene oxide is separated. Propane is completely or
partly separated from this further stream and the resulting propene
obtained, separated from propane or depleted in propane, is
preferably recycled into step a). In this case, preferably the same
amount of propane is removed, which is fed to step a) with the
mixture of propene and propane. The distillation of the permeate
may be carried out in two stages for this purpose, where in the
first distillation stage, the further stream consisting largely of
propene and propane is separated, and subsequently stream S1 is
separated in the second distillation stage. The distillation
however is preferably carried out in only one column with a side
draw, stream S1 being removed as a side stream and the further
stream consisting essentially of propene and propane being removed
as overhead product of the column.
In a further preferred embodiment, the organic phase P2 is
separated by distillation into a stream S1, comprising unreacted
propene and propene oxide formed as intermediate, and a stream S2,
depleted in propene and propene oxide, the stream S2 is separated
by nanofiltration into a retentate enriched in heteropolytungstate
and a permeate depleted in heteropolytungstate and the stream S1 is
recycled into the reaction of step a). This embodiment is
preferably used if the reaction in step a) of the process is
carried out in the presence of a solvent and the distillation is
then carried out such that the solvent remains in stream S2. The
solvent can then be removed from the permeate of the
nanofiltration, preferably by distillation, and can then be
recycled into the reaction of step a). Compared to the embodiment
described above, the embodiment with a separation of stream S1
prior to the nanofiltration has the advantage that a considerably
smaller stream is separated by the nanofiltration, which reduces
the apparatus size and the energy consumption of the
nanofiltration. If propene is used as a mixture with propane, in
this embodiment preferably a further stream is separated from
stream S1 by an additional distillation, which consists essentially
of propene and propane and from which propene oxide is separated,
before stream S1 is recycled into step a). Propane is completely or
partly separated from this further stream and the resulting propene
obtained, separated from propane or depleted in propane, is
preferably recycled into step a). In this case, preferably the same
amount of propane is separated which is fed to step a) with the
mixture of propene and propane.
In step d) of the process according to the invention,
1,2-propanediol is separated from the aqueous phase P1 separated in
step b). The 1,2-propanediol can be separated from the aqueous
phase by distillation, preferably by a two-stage distillation, in
which water is distilled off in the first stage and 1,2-propanediol
is distilled off in the second stage from the bottom product of the
first stage.
Prior to the separation of 1,2-propanediol, peroxides are
preferably removed by a catalytic hydrogenation. The hydrogenation
is preferably carried out using a supported hydrogenation catalyst
comprising one or more metals from the group of Ru, Rh, Pd, Pt, Ag,
Ir, Fe, Cu, Ni and Co on a support, wherein activated carbon,
SiO.sub.2, TiO.sub.2, ZrO.sub.2, Al.sub.2O.sub.3 and aluminium
silicates are preferred as support. Preference is given to
hydrogenation catalysts comprising ruthenium as active metal. The
catalytic hydrogenation is preferably carried out at a partial
hydrogen pressure of 5 to 300 bar and a temperature of 80.degree.
C. to 180.degree. C., preferably 90.degree. C. to 150.degree. C.
The hydrogenation catalyst may be used as a suspension or as a
fixed bed, a trickle bed hydrogenation with a fixed bed catalyst
being preferred. The hydrogenation can prevent problems due to
decomposition of hydrogen peroxide in a separation of
1,2-propanediol by distillation and reduce the by-products
1-hydroperoxy-2-propanol, 2-hydroperoxy-1-propanol and
hydroxyacetone formed in step a) to 1,2-propanediol, and can
thereby improve the yield of 1,2-propanediol.
In step d) of the process according to the invention, the aqueous
phase P1 is preferably separated by nanofiltration into a retentate
enriched in heteropolytungstate and a permeate depleted in
heteropolytungstate, the retentate is recycled into the reaction in
step a) and 1,2-propanediol is separated from the permeate. For the
nanofiltration in step d), a nanofiltration membrane is used which
retains peroxotungstate and heteropolyperoxotungstate in the
retentate and allows water and 1,2-propanediol to pass through with
the permeate. The nanofiltration is operated so that the solubility
limit of the heteropolytungstate in the retentate is not exceeded.
For a continuous reaction in step a), preferably that much water is
recycled to step a) with the retentate that a concentration of
1,2-propanediol in the aqueous phase P1 in the range of 10 to 30%
by weight results. By an appropriate recycling of water, on the one
hand formation of dipropylene glycol and tripropylene glycol in
step a) can be prevented and on the other hand the amount of water,
which has to be separated from 1,2-propanediol by distillation, can
be kept low. Membranes based on the polymers polyamide, polyether
sulphone, polysulphone and polyamide-imide can be used for the
nanofiltration. Suitable nanofiltration membranes are commercially
available, for example, from GE Water & Process Technologies
under the name DK Series, from Dow Water & Process Solutions
under the name DOW FILMTEC.TM. NF, from Hydranautics under the
names ESNA, ESP and SWC, from Toray Industries under the names
TM700 and TM800, from SolSep under the name NF 010206W, and also
from AMS Technologies under the names NanoPro.TM. A, NanoPro.TM. S
and NanoPro.TM. B.
In addition to the nanofiltration or as an alternative thereto,
tungstate and heteropolytungstate can be removed from the aqueous
phase P1 by adsorption on a support material. For such an
adsorption, preference is given to using a cationized inorganic
support material described in WO 2009/133053 on page 7, line 1 to
page 8, line 29. The adsorption on the support material and the
recovery of tungstate and heteropolytungstate adsorbed on the
support material is preferably carried out using the methods
described in WO 2009/133053 and WO 2013/110419. If the adsorption
is used in addition to a nanofiltration in step d), the adsorption
is preferably carried out after the nanofiltration in order to keep
the demand for support material low.
Nanofiltration and adsorption on a support material are preferably
carried out before the hydrogenation described above, in order to
avoid deactivation of the hydrogenation catalyst by tungstate or
heteropolytungstate.
In a preferred embodiment of the process according to the
invention, the aqueous phase P1 separated in step b) is brought
into contact with liquid propene in step d) to obtain an aqueous
phase P3 and an organic phase P4, the organic phase P4 is recycled
into the reaction of step a) and 1,2-propanediol is separated from
the aqueous phase P3. In this embodiment, preferably no separation
of tungsten from the aqueous phase P1 is carried out and tungsten
is separated from the aqueous phase P3, preferably by
nanofiltration and/or adsorption as described above for the aqueous
phase P1. The aqueous phase P1 is brought into contact with propene
preferably in an additional mixed reactor with a residence time in
the reactor which leads to a conversion of the hydrogen peroxide
present in the aqueous phase of at least 50%, preferably at least
80%. The bringing into contact in the additional reactor is carried
out preferably at a temperature of 60 to 100.degree. C. and a
pressure which is above the saturated vapour pressure of propene at
the selected temperature. The aqueous phase P1 is preferably
brought into contact with propene in a continuously operated
reactor, particularly preferably in a loop reactor. By the use of
an additional continuously operated reactor, a high conversion of
hydrogen peroxide can be achieved with an overall lower reactor
volume.
In this embodiment, propene is preferably supplied to the process
only in step d) and gets to the reaction of step a) with the
organic phase P4. If a phase transfer catalyst is used in the
process which, in the presence of hydrogen peroxide, transfers more
than half of the tungsten from the aqueous phase into liquid
propene, the aqueous phase P1 may also be brought into contact with
liquid propene in a countercurrent extraction, preferably a
countercurrent extraction column, and tungsten present in the
aqueous phase P1 is then recycled into step a) with the organic
phase P4.
FIG. 1 shows an embodiment of the process according to the
invention with a continuous reaction in step a) in a loop reactor
and a nanofiltration of the aqueous phase in step d). Propene (1),
hydrogen peroxide (2) and catalyst mixture (3) are fed to a
reaction loop in which the liquid biphasic mixture (6), comprising
an aqueous phase having a pH of at most 6 and an organic phase, is
circulated through a cooled tube bundle reactor (5) using a
circulating pump (4). A portion of biphasic mixture (6), which
corresponds to the amount fed of propene (1), hydrogen peroxide (2)
and catalyst mixture (3), is withdrawn from the reaction loop, and
this portion is separated in a phase separation vessel (7) into an
aqueous phase P1 (8) and an organic phase P2 (9). The organic phase
P2 (9) is recycled into the reaction loop. The aqueous phase P1 (8)
is separated by nanofiltration (10) into a retentate (11) enriched
in heteropolytungstate and a permeate (12) depleted in
heteropolytungstate. The retentate (11) is recycled into the
reaction loop. The permeate (12) is converted to a hydrogenated
permeate (15) in a catalytic hydrogenation (14) with hydrogen (13).
The hydrogenation reduces unreacted hydrogen peroxide to water and
the by-product hydroxyacetone to 1,2-propanediol. In a first
distillation (16), water (17) is distilled off from the
hydrogenated permeate (15) and in a second distillation (19),
1,2-propanediol (20) is distilled from the bottom product (18) of
the first distillation. In the bottoms of the second distillation,
water-soluble high boilers (21) arise, for example dipropylene
glycol. Inert gas (22) is supplied to the gas space of the phase
separation vessel (7) and an oxygen-containing gas stream (23) is
withdrawn to discharge oxygen formed by decomposition of hydrogen
peroxide and prevent formation of a flammable gas phase in the gas
space.
FIG. 2 shows an embodiment of the process according to the
invention, which additionally comprises a nanofiltration of the
organic phase with subsequent distillation in step c). The organic
phase P2 (9) is separated by nanofiltration (24) into a retentate
(25) enriched in heteropolytungstate and a permeate (26) depleted
in heteropolytungstate. The retentate (25) is recycled into the
reaction of step a). The permeate (26) is fed to a third
distillation (27) in which a stream S1 (28) is obtained as overhead
product, which comprises unreacted propene and propene oxide formed
as intermediate. The stream S1 (28) is recycled into the reaction
loop. Water-insoluble high boilers, for example degradation
products of the phase transfer catalyst, are discharged with the
bottom product (29) of the third distillation.
FIG. 3 shows an embodiment in which the sequence of nanofiltration
and distillation is exchanged in step c) compared to the process of
FIG. 2. In this embodiment, the organic phase P2 (9) is fed to the
third distillation (27). The stream S1 (28) obtained as overhead
product of the distillation, which comprises unreacted propene and
propene oxide formed as intermediate, is recycled into the reaction
loop. The bottom product (29) of the third distillation is
separated by nanofiltration (24) into a retentate (25) enriched in
heteropolytungstate and a permeate (26) depleted in
heteropolytungstate. The retentate (25) is recycled into the
reaction of step a).
FIG. 4 shows an embodiment in which the aqueous phase P1 is once
again brought into contact with propene in a reactor in step d) and
1,2-propanediol is separated from the resulting aqueous phase P3.
In this embodiment, the aqueous phase P1 (8) is fed to a second
reaction loop, to which the fed propene (1) is introduced in liquid
from and in which the resulting liquid biphasic mixture is
circulated through an additional reactor (30) with a circulating
pump. A portion of biphasic mixture is withdrawn from the reaction
loop, which corresponds to the amount of propene (1) and aqueous
phase P1 (8) fed, and this portion is separated in a phase
separation vessel (31) into an aqueous phase P3 (32) and an organic
phase P4 (33). The organic phase P4 (33) is recycled into the
reaction loop of the reaction of step a). 1,2-Propanediol (20) is
separated from the aqueous phase P3 (32) by nanofiltration (10),
catalytic hydrogenation (14), first distillation (16) and second
distillation (19), as described for the aqueous phase P1 of FIG. 1.
The retentate (11) is recycled into the first reaction loop.
LIST OF REFERENCE NUMBERS IN THE FIGURES
1 propene 2 hydrogen peroxide 3 catalyst mixture 4 circulating pump
5 cooled tube bundle reactor 6 biphasic mixture 7 phase separation
vessel 8 aqueous phase P1 9 organic phase P2 10 nanofiltration of
aqueous phase 11 retentate of nanofiltration 10 12 permeate of
nanofiltration 10 13 hydrogen 14 catalytic hydrogenation 15
hydrogenated permeate 12 16 first distillation 17 water 18 bottom
product of the first distillation 19 second distillation 20
1,2-propanediol 21 high boilers 22 inert gas 23 oxygen-containing
gas stream 24 nanofiltration of organic phase 25 retentate of
nanofiltration 24 26 permeate of nanofiltration 24 27 third
distillation 28 stream comprising propene and propene oxide 29
bottom product of the third distillation 30 additional reactor 31
phase separation vessel 32 aqueous phase P3 33 organic phase P4
EXAMPLES
Example 1, Preparation of Epoxidized Soy Fatty Acid Methyl
Ester
750 g of soy fatty acid methyl ester, 115 g of demineralized water,
13.8 g of REWOQUAT.RTM. 3099
(bis-(2-hydroxypropyl)-dimethylammonium methylsulphate vegetable
fatty acid diester), 3.6 g of sodium tungstate dihydrate and 1.2 g
of phosphoric acid were charged to a 2.5 l volume stirred vessel.
At 70.degree. C. and with stirring, 540 g of 28% by weight aqueous
hydrogen peroxide solution were added over 1 h with stirring. The
mixture was stirred for a further 1.5 h at 70.degree. C., cooled to
20.degree. C. and the epoxidized soy fatty acid methyl ester was
separated by phase separation as the light phase.
Example 2, Preparation of 1,2-propanediol from Propene and Hydrogen
Peroxide with Epoxidized Soy Fatty Acid Methyl Ester as Solvent
The reaction of propene with hydrogen peroxide was carried out at a
temperature of 78.degree. C. and a pressure of 4.2 MPa in a 0.45 l
volume loop reactor, which was operated at a circulation rate of 90
kg/h. Into the loop reactor were dosed 140 g/h of propene, 140 g/h
of a 20.0% by weight aqueous solution of hydrogen peroxide, 120 g/h
of an aqueous solution containing 10.0% by weight sodium tungstate
dihydrate and 24.0% by weight phosphoric acid, and 240 g/h of a
mixture of 8.3% by weight REWOQUAT.RTM. 3099 and 91.7% by weight
epoxidized soy fatty acid methyl ester from example 1. Biphasic
reaction mixture was withdrawn from the loop reactor in an amount
corresponding to the amounts dosed, the mixture was decompressed to
ambient pressure, whereupon dissolved propene outgassed and the
phases were then separated. After 5 h operation, 301 g of reaction
mixture were withdrawn within 30 min and, after the phase
separation, 138 g of aqueous phase and 163 g of organic phase were
obtained. The 1,2-propanediol content in the organic phase was
determined by .sup.1H-NMR. The hydrogen peroxide content in the
aqueous phase was determined by cerimetric titration. In a sample
of the aqueous phase, the hydrogen peroxide was reduced by addition
of sodium sulphite and then the contents of 1,2-propanediol,
hydroxyacetone, hydroxyacetone bisulphite adduct, acetaldehyde
bisulphite adduct, formic acid and acetic acid were determined by
.sup.1H-NMR and .sup.13C-NMR using maleic acid as external
standard.
The aqueous phase comprised 60 mmol/h hydrogen peroxide, which
gives a conversion of hydrogen peroxide of 93%. 26 mmol/h of
1,2-propanediol (3%) were obtained in the organic phase and, in the
aqueous phase, 377 mmol/h (46%) of 1,2-propanediol, 5 mmol/h of
hydroxyacetone (0.6%), 5 mmol/h of acetaldehyde, 2 mmol/h of acetic
acid and 4 mmol/h of formic acid (the figures in parentheses are
yields based on hydrogen peroxide used).
Example 3, Preparation of 1,2-propanediol from Propene and Hydrogen
Peroxide with Epoxidized Soy Fatty Acid Methyl Ester as Solvent
Example 2 was repeated, dosing 60 g/h of propene, 140 g/h of a
25.2% by weight aqueous solution of hydrogen peroxide, 220 g/h of
an aqueous solution containing 1.7% by weight sodium tungstate
dihydrate and 4.0% by weight phosphoric acid, and also 160 g/h of a
mixture of 12.3% by weight REWOQUAT.RTM. 3099 and 87.7% by weight
epoxidized soy fatty acid methyl ester into the loop reactor. After
5 h operation, 292 g of reaction mixture were withdrawn within 30
min and, after the phase separation, 204 g of aqueous phase and 88
g of organic phase were obtained.
The aqueous phase comprised 534 mmol/h hydrogen peroxide, which
gives a conversion of hydrogen peroxide of 49%. 14 mmol/h of
1,2-propanediol (1%) were obtained in the organic phase and, in the
aqueous phase, 263 mmol/h (25%) of 1,2-propanediol, 5 mmol/h of
hydroxyacetone (0.4%), 5 mmol/h of acetaldehyde, 2 mmol/h of acetic
acid and 4 mmol/h of formic acid.
Example 4, Preparation of 1,2-propanediol from Propene and Hydrogen
Peroxide with Epoxidized Soy Fatty Acid Methyl Ester as Solvent
Example 2 was repeated, dosing 120 g/h of propene, 140 g/h of a
25.1% by weight aqueous solution of hydrogen peroxide, 120 g/h of
an aqueous solution containing 10.1% by weight sodium tungstate
dihydrate and 24.0% by weight phosphoric acid, and also 160 g/h of
a mixture of 8.3% by weight REWOQUAT.RTM. 3099 and 91.7% by weight
epoxidized soy fatty acid methyl ester into the loop reactor. After
5 h operation, 305 g of reaction mixture were withdrawn within 30
min and, after the phase separation, 134 g of aqueous phase and 172
g of organic phase were obtained.
The aqueous phase comprised 74 mmol/h hydrogen peroxide, which
gives a conversion of hydrogen peroxide of 93%. 27 mmol/h of
1,2-propanediol (3%) were obtained in the organic phase and, in the
aqueous phase, 457 mmol/h (44%) of 1,2-propanediol, 8 mmol/h of
hydroxyacetone (0.8%), 8 mmol/h of acetaldehyde, 2 mmol/h of acetic
acid and 5 mmol/h of formic acid.
Example 5, Preparation of 1,2-propanediol from Propene and Hydrogen
Peroxide with Recycling of the Organic Phase
Example 2 was repeated, but using a portion of the combined organic
phases from Examples 2-4 instead of epoxidized soy fatty acid
methyl ester, dosing 30 g/h of propene, 93 g/h of a 29.9% by weight
aqueous solution of hydrogen peroxide, 40 g/h of an aqueous
solution containing 3.4% by weight sodium tungstate dihydrate and
6.9% by weight phosphoric acid, and also 160 g/h of a mixture of
1.5% by weight REWOQUAT.RTM. 3099 and 98.5% by weight of organic
phases from Examples 2-4. After 5 h operation, 919 g of reaction
mixture were withdrawn within 180 min and, after the phase
separation, 421 g of aqueous phase and 498 g of organic phase were
obtained.
The aqueous phase comprised 59 mmol/h hydrogen peroxide, which
gives a conversion of hydrogen peroxide of 93%. 13 mmol/h of
1,2-propanediol (2%) were obtained in the organic phase and, in the
aqueous phase, 290 mmol/h (35%) of 1,2-propanediol, 16 mmol/h of
hydroxyacetone (2%), 7 mmol/h of acetaldehyde, 6 mmol/h of acetic
acid and 9 mmol/h of formic acid.
Example 6, Preparation of 1,2-propanediol from Propene and Hydrogen
Peroxide with Recycling of the Organic Phase
Example 5 was repeated, but using a 30.4% by weight aqueous
solution of hydrogen peroxide. After 5 h operation, 1095 g of
reaction mixture were withdrawn within 210 min and, after the phase
separation, 488 g of aqueous phase and 607 g of organic phase were
obtained.
The aqueous phase comprised 62 mmol/h hydrogen peroxide, which
gives a conversion of hydrogen peroxide of 93%. 14 mmol/h of
1,2-propanediol (2%) were obtained in the organic phase and, in the
aqueous phase, 288 mmol/h (35%) of 1,2-propanediol, 17 mmol/h of
hydroxyacetone (2%), 8 mmol/h of acetaldehyde, 6 mmol/h of acetic
acid and 9 mmol/h of formic acid.
Example 7, Separation of Tungstate from the Aqueous and from the
Organic Phase of the Reaction Mixture of the Epoxidation
The separation of tungstate by nanofiltration was investigated in
each case for the combined aqueous phases of Example 5 and 6 and
the combined organic phases of Examples 5 and 6.
The nanofiltration was carried out as a dead-end filtration in a
stirred filtration cell (METcell) from Evonik MET. The separation
of tungstate from the aqueous phase was carried out using the GE DK
membrane from GE Water & Process Technologies or the
NanoPro.TM. B-4022 membrane from AMS Technologies. The separation
of tungstate from the organic phase was carried out using the
PuraMem.RTM. S 600 membrane from Evonik MET or the ONF-2 membrane
from GMT Membrantechnik. Prior to determining retention capacity
and permeability, the membranes for the filtration of aqueous phase
were conditioned with water and aqueous phase, and the membranes
for the filtration of organic phase were conditioned with organic
phase, at a stirring speed of 500 min.sup.-1 under the conditions
specified in Table 1.
TABLE-US-00001 TABLE 1 Pressure Temperature Filtration time
Membrane Filtered medium in MPa in .degree. C. in min GE DK Water
2.0 20 23 aqueous phase 3.0 20 137 NanoPro .TM. Water 2.0 20 40
B-4022 aqueous phase 3.0 20 160 PuraMem .RTM. organic phase 2.0 20
29 S 600 3.0 20 114 ONF-2 organic phase 3.9 83 315
The filtration conditions for determining retention capacity and
permeability are listed in Tables 2-5 and the filtration
experiments were conducted at a stirring speed of 500 min.sup.-1.
The concentrations of tungsten and nitrogen in the phase used
(feed), in the retentate and in the permeate and the retention
capacity for tungsten and phase transfer catalyst calculated
therefrom are listed in Tables 6 and 7. The retention capacity was
calculated as 1-(permeate concentration)/(retentate concentration)
at each given time point.
TABLE-US-00002 TABLE 2 Filtration of 182 g of aqueous phase with GE
DK membrane Cumulative Permeability Filtration Pressure Temperature
mass of in kg time in min in MPa in .degree. C. permeate in g
m.sup.-2h.sup.-1bar.sup.-1 0 3.0 20 0 63 3.0 20 18.0 0.11 129 3.0
20 36.1 0.11 205 3.0 20 54.4 0.10 285 3.0 20 72.5 0.10 372 3.0 20
89.3 0.09
TABLE-US-00003 TABLE 3 Filtration of 180 g of aqueous phase with
NanoPro .TM. B-4022 membrane Cumulative Permeability Filtration
Pressure Temperature mass of in kg time in min in MPa in .degree.
C. permeate in g m.sup.-2h.sup.-1bar.sup.-1 0 4.5 20 0 73 4.5 20
15.9 0.06 169 4.5 20 29.7 0.047 298 4.5 20 45.6 0.040 410 4.5 20
57.7 0.037
TABLE-US-00004 TABLE 4 Filtration of 197 g of organic phase with
PuraMem .RTM. S 600 membrane Cumulative Permeability Filtration
Pressure Temperature mass of in kg time in min in MPa in .degree.
C. permeate in g m.sup.-2h.sup.-1bar.sup.-1 0 4.0 21 0 385 4.0 81
22.1 0.017 745 4.0 81 40.4 0.016 1350 4.0 82 60.0 0.013 1985 3.9 80
75.9 0.011 2780 3.9 81 88.6 0.009
TABLE-US-00005 TABLE 5 Filtration of 209 g of organic phase with
ONF-2 membrane Cumulative Permeability Filtration Pressure
Temperature mass of in kg time in min in MPa in .degree. C.
permeate in g m.sup.-2h.sup.-1bar.sup.-1 0 4.0 21 0 930 4.0 82 22.8
0.007 1875 4.0 83 40.0 0.006 2940 3.9 82 57.5 0.005
TABLE-US-00006 TABLE 6 Nanofiltration of aqueous phase Concen-
Concen- tration tration Tungstate PTC Sample of tungsten of
nitrogen retention retention Membrane analyzed in ppm in ppm in %
in % GE DK Feed 66 84 Retentate 100 155 after 372 min Permeate n.d.
18 n.d. 84 after 372 min NanoPro .TM. Feed 66 84 B-4022 Retentate
70 100 after 410 min Permeate 22 25 69 75 after 410 min n.d.: not
determined
TABLE-US-00007 TABLE 7 Nanofiltration of organic phase Concen-
Concen- tration of tration PTC tungsten of nitro- Tungstate reten-
Sample in % by gen retention tion Membrane analyzed weight in ppm
in % in % PuraMem .RTM. Feed 2.1 1800 S 600 Retentate 3.8 2950
after 46 min Permeate 0.4 450 89 85 after 46 min ONF-2 Feed 2.1
1800 Retentate 2.7 1850 after 49 min Permeate 0.5 18 81 99 after 49
min
Example 8, Preparation of 1,2-Propanediol from Propene and Hydrogen
Peroxide with a C10 Aromatic Compound Mixture as Solvent
The reaction of propene with hydrogen peroxide was carried out at a
temperature of 78.degree. C. and a pressure of 4.2 MPa in a 0.5 l
volume loop reactor, which was operated at a circulation rate of 90
kg/h. Into the loop reactor were dosed 90 g/h of propene, 140 g/h
of a 20.1% by weight aqueous solution of hydrogen peroxide, 120 g/h
of an aqueous solution, containing 10.1% by weight sodium tungstate
dihydrate, 24.0% by weight phosphoric acid and 1.5% by weight
hydrogen peroxide, whose pH had been adjusted to 1.5 with solid
sodium hydroxide, and also 240 g/h of a mixture of 5.7% by weight
trioctylamine and 94.3% by weight Hydrosol A 200 ND (low napthalene
C10-aromatic compound mixture, DHC Solvent Chemie). Biphasic
reaction mixture was withdrawn from the loop reactor in an amount
corresponding to the amounts dosed, 262 g/h of aqueous phase were
separated from organic phase and gas phase in a first phase
separation vessel at 1.6 MPa and 301 g/h of organic phase were
separated from the gas phase in a second phase separation vessel at
the same pressure. 50 Nl/h of nitrogen were dosed into the second
phase separation vessel, gas phase was removed via a
pressure-holding valve and the oxygen content in this gas phase was
determined using a paramagnetic oxygen sensor. Without pressure
reduction, the propene oxide content in the organic phase was
determined by GC-MS. The pH and the hydrogen peroxide content in
the aqueous phase was determined by cerimetric titration. In a
sample of the aqueous phase, the hydrogen peroxide was reduced by
addition of sodium sulphite and then the contents of
1,2-propanediol, dipropylene glycol, hydroxyacetone, hydroxyacetone
bisulphite adduct, acetaldehyde bisulphite adduct, formic acid and
acetic acid were determined by .sup.1H-NMR and .sup.13C-NMR using
maleic acid as external standard.
1 mmol/h of oxygen was obtained in the gas phase. The aqueous phase
had a pH of 2.0 and comprised 223 mmol/h hydrogen peroxide, which
gives a conversion of hydrogen peroxide of 75%. 27 mmol/h of
propene oxide (3%) were obtained in the organic phase and, in the
aqueous phase, 310 mmol/h (35%) of 1,2-propanediol, 16 mmol/h (2%)
of dipropylene glycol, 13 mmol/h of hydroxyacetone (1.5%), 11
mmol/h of acetaldehyde, 9 mmol/h of acetic acid and 6 mmol/h of
formic acid (the figures in parentheses are yields based on
hydrogen peroxide used).
Example 9, Preparation of 1,2-propanediol from Propene and Hydrogen
Peroxide with Recycling of the Organic Phase
Example 8 was repeated, dosing into the loop reactor 90 g/h of
propene, 140 g/h of a 20.3% by weight aqueous solution of hydrogen
peroxide, 120 g/h of an aqueous solution, containing 1.5% by weight
sodium tungstate dihydrate, 3.5% by weight phosphoric acid and 0.1%
by weight of hydrogen peroxide, whose pH had been adjusted to 1.5
with solid sodium hydroxide, and also 240 g/h of a mixture of 0.6%
by weight trioctylamine and 99.4% by weight of organic phase from
example 8 depressurized to ambient pressure.
8 mmol/h of oxygen were obtained in the gas phase. The aqueous
phase had a pH of 1.7 and comprised 124 mmol/h hydrogen peroxide,
which gives a conversion of hydrogen peroxide of 85%. 25 mmol/h of
propene dioxide (3%) were obtained in the organic phase and, in the
aqueous phase, 438 mmol/h (52%) of 1,2-propanediol, 21 mmol/h
(2.5%) of dipropylene glycol, 24 mmol/h of hydroxyacetone (3%), 11
mmol/h of acetaldehyde, 9 mmol/h of acetic acid and 12 mmol/h of
formic acid.
Example 10, Preparation of 1,2-propanediol from Propene and
Hydrogen Peroxide with Recycling of the Organic Phase
Example 9 was repeated, using a 20.0% by weight aqueous solution of
hydrogen peroxide and organic phase from example 9 depressurized to
ambient pressure.
24 mmol/h of oxygen were obtained in the gas phase. The aqueous
phase had a pH of 1.8 and comprised 143 mmol/h hydrogen peroxide,
which gives a conversion of hydrogen peroxide of 83%. 26 mmol/h of
propene dioxide (3%) were obtained in the organic phase and, in the
aqueous phase, 394 mmol/h (48%) of 1,2-propanediol, 19 mmol/h
(2.3%) of dipropylene glycol, 21 mmol/h of hydroxyacetone (2.5%),
12 mmol/h of acetaldehyde, 10 mmol/h of acetic acid and 6 mmol/h of
formic acid.
Example 11, Preparation of 1,2-Propanediol from Propene and
Hydrogen Peroxide Using a C10-Aromatic Compound Mixture as Solvent
with Separation of Tungstate from the Aqueous and Organic Phase
Example 10 was repeated, dosing into the loop reactor 120 g/h of
propene, 140 g/h of a 20.4% by weight aqueous solution of hydrogen
peroxide, 120 g/h of an aqueous solution, containing 16.1% by
weight sodium tungstate dihydrate, 25.6% by weight phosphoric acid
and 1.5% by weight hydrogen peroxide, whose pH had been adjusted to
1.5 with solid sodium hydroxide, and also 320 g/h of a mixture of
2.0% by weight trioctylamine and 98.0% by weight Hydrosol A 200 ND
(low napthalene C10 aromatic compound mixture, DHC Solvent
Chemie).
0.1 mmol/h of oxygen were obtained in the gas phase. The aqueous
phase had a pH of 2.0 and comprised 58 mmol/h hydrogen peroxide,
which gives a conversion of hydrogen peroxide of 94%. 17 mmol/h of
propene oxide (2%) were obtained in the organic phase and, in the
aqueous phase, 420 mmol/h (50%) of 1,2-propanediol, 20 mmol/h
(2.4%) of dipropylene glycol, 12 mmol/h of hydroxyacetone (1%), 10
mmol/h of acetaldehyde, 6 mmol/h of acetic acid and 4 mmol/h of
formic acid.
After depressurizing the reaction mixture and phase separation, the
separation of tungstate by nanofiltration were investigated
separately for the resulting aqueous phase and organic phase. The
nanofiltration was carried out as a dead-end filtration in a
stirred filtration cell (METcell) from Evonik MET. The separation
of tungstate from the aqueous phase was carried out using the GE DK
membrane from GE Water & Process Technologies. The separation
of tungstate from the organic phase was carried out using the ONF-2
membrane from GMT Membrantechnik. Prior to determining retention
capacity and permeability, the membranes for the filtration of
aqueous phase were conditioned with water and aqueous phase, and
the membranes for the filtration of organic phase were conditioned
with organic phase, at a stirring speed of 500 min.sup.-1 under the
conditions specified in Table 8.
TABLE-US-00008 TABLE 8 Pressure Temperature Filtration time
Membrane Filtered medium in MPa in .degree. C. in min GE DK Water
3.0 20 17 aqueous phase 3.0 20 438 ONF-2 organic phase 3.0 20
34
The filtration conditions for determining retention capacity and
permeability are listed in Tables 9 and 10 and the filtration
experiments were conducted at a stirring speed of 500 min.sup.-1.
The concentrations of tungsten and nitrogen in the phase used
(feed), in the retentate and in the permeate and the retention
capacity for tungsten and phase transfer catalyst calculated
therefrom are listed in Tables 11 and 12. The retention capacity
was calculated as 1-(permeate concentration)/(retentate
concentration) at each given time point.
TABLE-US-00009 TABLE 9 Filtration of 183 g of aqueous phase with GE
DK membrane Cumulative Permeability Filtration Pressure Temperature
mass of in kg time in min in MPa in .degree. C. permeate in g
m.sup.-2h.sup.-1bar.sup.-1 0 3.0 24 0 98 3.0 24 18.0 0.071 198 3.0
24 36.2 0.071 314 3.0 24 54.4 0.067 470 3.0 24 72.8 0.062 560 3.0
24 90.0 0.062
TABLE-US-00010 TABLE 10 Filtration of 200 g of organic phase with
ONF-2 membrane Cumulative Permeability Filtration Pressure
Temperature mass of in kg time in min in MPa in .degree. C.
permeate in g m.sup.-2h.sup.-1bar.sup.-1 0 3.0 25 0 10 3.0 25 20.2
0.772 21 3.0 25 40.0 0.735 32 3.0 25 59.8 0.710 46 3.0 25 79.5
0.667 62 3.0 25 100.3 0.625
TABLE-US-00011 TABLE 11 Nanofiltration of aqueous phase Concen-
Concen- tration tration Tungstate PTC Sample of tungsten of
nitrogen retention retention Membrane analyzed in ppm in ppm in %
in % GE DK Feed 21000 51 Retentate after 40000 58 560 min Permeate
after 2800 39 93 33 560 min
TABLE-US-00012 TABLE 12 Nanofiltration of organic phase Concen-
Concen- Tung- tration tration state PTC of tungsten of nitrogen
retention retention Membrane Sample analyzed in ppm in ppm in % in
% ONF-2 Feed 15000 1650 Retentate after 29000 3300 62 min Permeate
after 7 210 99.998 94 62 min
* * * * *